Hybrid Calycanthus plant named ‘Venus’

ABSTRACT

Calycanthus  cultivar ‘Venus’ is a medium-sized, multi-stemmed shrub producing large, yellow-green flower buds that open to unique large, white magnolia-like flowers with yellow and purple infusions in the center. The flowers open widely, such that all of the tepals are visible, and are fragrant with the fruity aroma of strawberries and melons.

Latin name of the genus and species: The Latin name of the novel hybridcultivar disclosed herein is Calycanthus(chinensis×floridus)×Calycanthus (chinensis×occidentalis) ‘Venus’.

Variety denomination: The Calycanthus hybrid disclosed herein has beengiven the variety denomination ‘Venus’.

BACKGROUND OF THE INVENTION

Calycanthus are deciduous shrubs that are commonly grown as ornamentallandscape plants. There are three species of Calycanthus. Calycanthusfloridus (common sweetshrub, Carolina allspice, Carolina sweetshrub,strawberry-shrub, bubby blossom, sweet bubby, sweet Bettie, spicebush)is found throughout much of the Eastern United States and commonly growsas an understory shrub in mixed deciduous forests, often along streamsand in moist woodlands. Plant height can vary and ranges from 1 to 2.5meters, growing as multi-stemmed shrubs with suckering shoots arisingfrom the base and roots. Fall color can be an attractive buttery yellow.The flowers range in size (2-3 cm across) with tepals that vary fromreddish purple to a dark chocolate brown. The fragrance is variable, butcan have a pleasant fruity aroma. Older synonyms for this speciesinclude Calycanthus glaucus, C. fertilis, C. floridus var. laevigatus,C. floridus var. oblongifolius, C. nanus, C. brockianus, and C. mohrii.

Calycanthus occidentalis (California sweetshrub) is naturally found inWashington and California growing as an understory species along streamsand on moist canyon slopes. Although similar to the Carolina sweetshrub,the California species is larger in almost all respects with the plantsgrowing to over 3.5 meters tall. The flowers, although slightly larger(2 to 4 cm across) and a brighter red, are typically not as fragrant asthose produced by C. floridus.

The Chinese wax shrub Calycanthus chinensis (Sinocalycanthus chinensis)is a rare species native to the Zheijang Province in southeast China.This medium-sized shrub grows to 1 to 2.7 meters tall with large, glossyleaves. The flowers open more completely (up to 8 cm in diameter) thando North American species and are multicolored with the outer perianthwhorl being whitish pink and the inner whorl being a strong yellow withoccasional purple streaks at the base, with no fragrance.

Calycanthus is becoming increasingly popular as a landscape plant foruse as a shrub border, foundation plant or a naturalizing plant.Calycanthus has few disease or insect pest problems. Severalhorticultural varieties of Calycanthus floridus are known including‘Athens’ (unpatented), ‘Edith Wilder’ (unpatented), and ‘Michael Linsey’(unpatented). As far as the inventors are aware, no varieties ofCalycanthus are patented.

The present invention relates to a new and distinct hybrid variety ofCalycanthus which is known botanically as Calycanthus L. ‘Venus’(×Sinocalycalycanthus ‘Venus’ Lasseigne and Fantz) and has been giventhe cultivar name ‘Venus’. Calycanthus ‘Venus’ is suitable for use as amedium-sized ornamental landscape shrub.

There is some disagreement about the classification of the Chinese waxshrub. Some consider that the proper classification is in the genusCalycanthus (i.e., Calycanthus chinensis, W. C. Cheng and S. Y. Chang);but another treatment places it in a separate genus (Sinocalycanthuschinensis, W. C. Cheng and S. Y. Chang). However, recent molecularphylogeny data (Zhou, S., S. Renner, and J. Wen. Molecular phylogeny andinter and intracontinental biogeography of Calycanthaceae. InPreparation) has indicated that this species is genetically embeddedamong other Calycanthus species providing strong justification to placethe Asian species within the genus Calycanthus. Based on this treatment,the proper scientific name for the hybrid of the invention is:Calycanthus L. ‘Venus’. If future taxonomic treatments place the Chinesewax shrub into the genus Sinocalycanthus, then the proper scientificname for this new hybrid would be: ×Sinocalycalycanthus Lasseigne andFantz ‘Venus’.

Parentage. Calycanthus cultivar ‘Venus’ resulted from controlledpollinations using three different species (female parents are listedfirst for each combination; see FIG. 4):H2000-14-001 (Calycanthus chinensis×Calycanthus floridus ‘Athens’)[unpatented]×H2000-17-002 (Calycanthus chinensis×Calycanthusoccidentalis) [unpatented].

Calycanthus ‘Venus’ originated from a controlled breeding program, andwas selected from seed germinated in the Fall of 2001 in a cultivatedarea at the North Carolina State University, Mountain HorticulturalCrops Research Station, Fletcher, N.C., USA.

Asexual reproduction. The first asexual propagation of ‘Venus’ wascarried out in June, 2002 by rooting stem cuttings at North CarolinaState University, Mountain Horticultural Crops Research Station,Fletcher, N.C., USA. Calycanthus cultivar ‘Venus’ roots readily (>90%)from firm, subterminal, softwood cuttings when treated with a basal dipof 5,000-10,000 ppm indole butyric acid (potassium salt) in water. Thecombination of distinguishing characteristics disclosed herein for‘Venus’ have remained stable and true to type through successive cyclesof asexual propagation.

SUMMARY OF THE INVENTION

Calycanthus cultivar ‘Venus’ is a medium-sized, multi-stemmed shrubproducing large, yellow-green flower buds that open to unique large,white magnolia-like flowers with yellow and purple infusions in thecenter. The flowers open widely, such that all of the tepals arevisible, and are fragrant with the fruity aroma of strawberries andmelons.

This combination of traits has been consistently observed anddistinguishes ‘Venus’ from the parental species as well as othercommercial cultivars known to the inventors.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying photographs exemplify the distinguishing traits of thenew Calycanthus ‘Venus’. All photographs are of greenhouse-grown plantsin Fletcher, N.C. The photographs were produced using conventionaltechniques and although colors may appear different from actual colorsdue to lighting and the equipment used, they are as accurate as possibleby conventional photography.

FIG. 1 is a top view of the original plant growing in a 7-galloncontainer at approximately 18-months of age.

FIG. 2 is a side view of the flower bud.

FIG. 3 illustrates the open flower.

FIG. 4 illustrates the pedigree of Calycanthus ‘Venus’ including flowersof ‘Venus’ as well as progenitor varieties. Female parents are listedfirst for each cross.

DETAILED BOTANICAL DESCRIPTION

The following is a detailed description of the botanical characteristicsof the new and distinct Calycanthus cultivar ‘Venus’. Colordeterminations are in accordance with the 2001 Edition of The RoyalHorticultural Society Colour chart. Where dimensions, sizes, color andother characteristics are given, it is to be understood that suchcharacteristics are approximations of averages and ranges as measuredunder growing conditions in Fletcher, N.C. and are as accuratelyreported as practicable.

The following description of ‘Venus’ is from 18 month-old plants grownin a greenhouse in Spring, 2003. Calycanthus ‘Venus’ has not beenobserved under all possible conditions; it will be appreciated thatphenotypic differences may occur with variations in environmental,climactic and cultural conditions.

-   Classification: Shrub-   Type: Deciduous-   Form: Multi-stemmed shrub-   Shape: Rounded to spreading-   Size: Size at maturity is not yet known. The most mature specimen of    the variety is 75 cm tall and 75 cm wide at 1.5 years of age (FIG.    1). Based on this specimen's observed growth rate and the size of    its parents, ‘Venus’ is anticipated to be a medium-sized shrub    reaching 1.5 to 2.5 meters in height.-   Vigor: Growth rate is moderate. Vegetative shoots typically grow 25    to 75 cm per growing season. Flowering shoots typically grow 10 to    15 cm before flowering.-   Shoots: Young shoots are glabrous and yellow-green (ranging from    144A to 144B) to green (ranging from 143A to 143B) with faint white    lenticels (155 C). Opposite or sub-opposite arrangement. Typical    shoot length: 25 to 75 cm; typical shoot diameter: 4 to 8 mm;    typical internode length: 3 to 9 cm.-   Bark: Branches and trunk have greyed-green bark (ranging from 197B    to 197D) with greyed-orange lenticels (ranging from 165C to 165D).-   Trunk: Typical trunk diameter of an 18 month-old plant is 1 to 2 cm    measured 2 cm above the soil.-   Branches: Typical branch length of an 18 month-old plant: 30 to 65    cm; typical branch diameter: 6 to 10 mm.-   Foliage:    -   -   Size.—Leaves vary considerably in size depending on the            environment and time of year, but typically range from 7 to            20 cm in length and 5 to 10 cm in width.        -   Form.—Simple. Opposite or sub-opposite in arrangement. Shape            elliptical to ovate. Apex acuminate. Base rounded to acute,            rarely slightly oblique.        -   Margin.—Entire.        -   Veination.—5 to 7 pairs of veins (opposite).        -   Surface.—Slightly scabrous above (adaxial). Glabrous below            (abaxial).        -   Petioles.—Range from 1 to 1.5 cm in length, 1 to 2 mm in            diameter and are slightly pubescent. Typical petiole color            is yellow-green (145A).        -   Summer color.—Young leaves are yellow-green (ranging from            144A to 144B) to green (ranging from 143A to 143B) and            glossy. Mature leaves are green (ranging from 137A to 137C)            on adaxial (somewhat glossy) and abaxial (dull, glaucescent)            sides.        -   Fall color.—Fall foliage ranges from a buttery yellow            (ranging from 11C to 11D) to brown-yellow (ranging from 24C            to 24D) with some greyed-orange (ranging from N167C to            N167D) for both upper and lower leaf surfaces.-   Inflorescence: Calycanthus ‘Venus’ produces solitary, complete    flowers with 20 to 30 tepals in one imbricate series on a 10 to 20    mm stalk at the terminals of current season's growth. These flowers    are magnolia-like and open fully such that all of the tepals are    visible.-   Flower buds (FIG. 2):    -   -   Size and shape.—Ellipsoid, 2 to 3.5 cm in length and 2 cm in            diameter.        -   Color.—Outer tepals are primarily green-yellow (1D) with            some yellow-green (ranging from 144C to 144D).-   Open flowers (FIG. 3):    -   -   Flower size.—Ranges from 7.5 to 11.5 cm in diameter. Flower            depth ranges from 3 to 5 cm.        -   Color.—Upper surface of outer (distal) tepals is primarily            white (ranging from 155A to 155D) with some green-yellow            (1D). Lower surface of outer tepals is white (ranging from            155A to 155D) with some green-yellow (1D) and yellow-green            (ranging from 144C to 144D). Upper surface of inner            (proximal) tepals is white (ranging from 155A to 155D) and            yellow (5C) with a slight blush of red-purple (60C) on edges            and base. The lower surface of the inner tepals is similar            to the upper surface in color, but with less red-purple            (60C).        -   Bracts.—One to two bracts subtending flowers; shape:            lanceolate; length: 1 to 1.5 cm; width: 5 to 7 mm; apex:            acuminate; base: cuneate; color: green (ranging from 137A to            137C) on both surfaces. Margin is entire.-   Fragrance: Fruity aroma similar to ripe strawberries and melons.-   Peduncle: Peduncles range from 1 to 2 cm in length and 2 to 4 mm in    diameter. Color is green (ranging from 143C to 144B) with a blush of    red (44C) on upper surface.-   Bloom time: In Fletcher, N.C., flowers begin to bloom in early May    and continue sporadically throughout June and July. Lastingness of    bloom ranges from 2 to 4 days.-   Fruit: Fruit have not been observed even with controlled    pollination.-   Reproductive structures:    -   -   Pistils.—Filamentous with no clear distinction between            stigma and style, translucent, 4 to 5 mm in length, 7 to 15            pistils per flower.        -   Stamens.—Ten to 20 stamens per flower. Anthers range from 4            to 6 mm in length; filament ranges from 0.5 to 1.5 mm in            length. Anthers are yellow (11B), and filaments are            green-yellow (1D).        -   Ovary.—Ranges from 7 to 12 mm in length, 7 to 15 mm in            width. Color is yellow-green (ranging from 145A to 145D), 1            ovary per flower.        -   Pollen.—Fusiform to rounded in shape, 0.03 to 0.06 mm in            length, 0.02 to 0.05 mm in width. Pollen is yellow (11B),            translucent to slightly opaque.-   Cultural requirements, disease and pest resistance/susceptibility:    Cultural requirements, disease and pest resistance/susceptibility    for Calycanthus ‘Venus’ appear to be similar to other Calycanthus.    No unique problems have been found for this plant, and no particular    resistance or susceptibility to disease or pests has been observed.    This variety can be grown in full-sun to shade with best growth on    moist sites that do not become overly dry. Calycanthus ‘Venus’    tolerates a range of soil pH from about 4.5 to 6.5.-   Cold hardiness: Based on the parent species, ‘Venus’ is estimated to    be cold hardy in USDA zones 5-9. ‘Venus’ specimens have been    observed to survive at 0° F.-   Comparison with related species: Calycanthus cultivar ‘Venus’ has a    combination of traits that produces a more attractive, fragrant    ornamental shrub as compared with other Calycanthus species. In    particular, ‘Venus’ produces a large, white magnolia-like flower    that is unique among Calycanthus. ‘Venus’ can be readily    distinguished from the parental species by the combination of size,    color, shape, habit and fragrance of its flowers (see, e.g., FIG.    4). For example, Calycanthus floridus (including the ‘Athens’    cultivar) produces a relatively small, sometimes fragrant maroon to    yellow-green flower, which does not completely open. Calycanthus    occidentalis also produces a relatively small (as compared with    ‘Venus’) brown to reddish-brown flower, which does not open and    which has little or no fragrance. The C. chinensis species has a    larger (as compared with C. floridus and C. occidentalis), flat    opened flower, which has no fragrance. In contrast, ‘Venus’ produces    very large magnolia-like flowers which are unique among Calycanthus,    have a strong fragrance, and are held up above the foliage. The    flowers are white with yellow and purple infusions at the center.    Further comparisons are provided in Table 1.

TABLE 1 Comparison with Related Species Charac- Calycanthus CalycanthusCalycanthus Calycanthus teristic ‘Venus’ floridus occidentalis chinensisSize of 7.5-11.5 2-3 cm. 2-4 cm. 5-8 cm. Flower cm. Color of Outertepals: Typically Reddish- Outer tepals Flower Upper reddish- brown.whitish-pink. surface is brown. Inner tepals white with Yellow- yellow.some green- green for yellow; ‘Athens’. lower sur- face is white withsome green-yellow and yellow- green. Inner tepals: Upper surface iswhite and yellow with a slight blush of red-purple on edges and base;lower surface is similar, but with less red-purple. Flower Fruity.Variable. Little or None. Fragrance Often fruity. none. Tepal Imbricate.Imbricate. Imbricate. Two-series. Arrangement

-   Comparison with parental cultivars: ‘Venus’ is easily distinguished    from either parent based on open flower color (see, FIG. 4). Flowers    of the female parent H2000-14-001 have greyed-purple (183A) tepals    (both surfaces) with pale yellow (4C) tips on the innermost tepals.    Flowers of the male parent H2000-17-002 have red-purple (59B) tepals    (both surfaces) with distinct yellow (ranging from 4A to 4B) tips on    the innermost tepals. Flowers of ‘Venus’ are primarily white with    some green-yellow, yellow, yellow-green and red-purple as described    above under “Open Flowers, Color” and in Table 1 (see also, FIG. 3).

1. A new and distinct hybrid cultivar of Calycanthus plant named‘Venus’, substantially as illustrated and described herein.